What's Up With My Greenfinches?

Today at about 4 pm I was sitting in my garden when a whole flock of greenfinches (at least one of whom might have been a siskin) arrived.  I usually get three or four at any one time, but there were at least ten or twelve of them (I tried to count properly, but they would keep moving around...).

They ignored the seed feeder which is their usual haunt and went straight for the two peanut feeders.  The ones who couldn't fit on the peanuts spent their time ground feeding, something I have hardly ever seen them do before.  There was quite a lot of drinking out of the bird bath and water bucket too. 

But the main thing that was different was that they were really squabbly, and spent lots of time shoving each other off the feeders, including some really spectacular aerial fighting (none of which, naturally, I managed to capture on camera).  I think it was the males doing most of the fighting - they're the brighter green ones, right?  The fighting thing was odd, because they usually feed very peacefully.

All the time this was going on, they were making a huge amount of noise; not much actual singing but a lot of "chip chip," if you know what I mean.  I thought at first it was an alarm call, but they were there feeding away for ages and didn't seem at all distressed, so I don't know what they were talking about.

The whole thing reminded me slightly of a deep south bar brawl (not that I've ever been in one).  Was this all because they are getting a bit... er... frisky?

BB

PS What's the proper plural of finch - finch or finches?